This is a revision of Program Project proposal 1 PO1 HD-047609 "Gene-Environment Interactions in Human Parturition" that was submitted in October 2003, reviewed by an NICHD Special Emphasis Panel, and received a priority score of 199 (30th percentile). In this research program we proposed to identify the genef/c and environmental determinants of the length of human gestation/ timing of onset of spontaneous parturition, and to model the gene, environment, and maternal-fetal interactions that may underlie the risk of premature birth among three racial/ ethnic populations: African-Americans, Hispanics and nonHispanic Whites. The previous review commented very favorably on all aspects of the Clinical Core as proposed, and noted that a major advantage is the availability of the large clinical population, phenotype data that has already been collected, preliminary response analysis, preliminary study for DMA recovery, and superb facilities. This would enhance the efficacy of the proposed Program Project and also lead to a dramatic cost reduction. The review did not raise any concerns. The Core received a priority score of 100.